One of the country's largest employer groups says the Senate's change to the small business threshold to 20 is both reasonable and necessary and should be accepted by the government.
Australian Chamber of Commerce and Industry (ACCI) chief executive Peter Anderson said on Friday the employment mix of small business had changed over the years, making 20 employees a more realistic definition than 15.
Independent Nick Xenophon and Family First's Steve Fielding sided with the coalition in an overnight vote to amend Labor's Fair Work bill making special rules for unfair dismissal apply to businesses with 20 or fewer employees rather than those with 15 or less.
Mr Anderson said small business tended to employ fewer permanent staff especially since the introduction of unfair dismissal laws under the Keating government.
But the ACTU said on Friday the amendment must be dropped because the shift to a definition of 20 employees would mean more than a million workers will miss out.
The special unfair dismissal rules the government would provide protection to workers in businesses with 15 or fewer staff provided they have been in the job for 12 months.
For employees in businesses with more than 15 staff, the unfair dismissal protection would apply provided they had been employed for six months.
Treasurer Wayne Swan confirmed the government would use its numbers in the lower house to reject the amended Fair Work Bill, which was passed by the Senate earlier today.
The bill will be sent back to the upper house when the House of Representatives resumes sitting on Friday morning.
"We are not going to be doing anything other than sending that legislation back up in the Senate," Mr Swan told Sky News.
"We are absolutely determined to keep our promise to the Australian people."
Both houses of parliament will convene for a rare Friday sitting as the government races to pass its own bill ahead of a seven-week break.
Mr Swan refused to say whether the government would have a trigger for a double dissolution of parliament if the bill was rejected by the Senate.
